Convert ShapeFile to WGS 84 using GDAL

gdal.py

# with gdal
import osgeo.ogr


w = osgeo.ogr.Open('BATI_INDIFFERENCIE.SHP')

layer = f.GetLayer(0)

# get source SRID
source = layer.GetSpatialRef()

# load generic SRID aka. WGS84 with 3 coordinates
target = osgeo.osr.SpatialReference()
WGS84_3D = 4979
target.ImportFromEPSG(WGS84_3D)

# create transformation to share between several transformations
transform = osgeo.osr.CoordinateTransformation(source, target)

# get a geometry
feature = layer.GetFeature(0)
geometry = layer.geometry()

# transform geometry
geometry.Transform(transform)

# or more easily
geometry.TransformTo(target)
feature.ExportToJson()